Field of the Disclosure
[0001] The disclosure relates generally to the field of circuit protection devices and,
more particularly, to a current sensor with a diagnostic feature for in-situ feedback.
Background of the Disclosure
[0002] Current sensors are often used in overcurrent protection devices, including in short-circuit
protection devices. These devices are used as safety elements in critical applications,
such as electric vehicles (EV). Oftentimes, current sensors are factory calibrated
or compensated. However, prior art approaches lack effective in-situ solutions to
periodically check if the current sensor is still operational and calibrated.
[0003] It is with respect to this and other deficiencies of the prior art that the current
disclosure is provided.
Summary of the Disclosure
[0004] The Summary is provided to introduce a selection of concepts in a simplified form,
the concepts further described below in the Detailed Description. The Summary is not
intended to identify key features or essential features of the claimed subject matter,
nor is the Summary intended as an aid in determining the scope of the claimed subject
matter.
[0005] In one approach according to the present disclosure, An apparatus may include a current
sensor coupled to a busbar, the current sensor comprising a coil, wherein a current
flowing through the busbar generates a first magnetic field detectable by the current
sensor, wherein the coil is operable to generate a second magnetic field, and wherein
by orienting the coil, the current sensor will receive part of the second magnetic
field, superposed to the first magnetic field.
Brief Description of the Drawings
[0006] The accompanying drawings illustrate exemplary approaches of the disclosed embodiments
so far devised for the practical application of the principles thereof, and in which:
FIG. 1 depicts a current sensor assembly according to embodiments of the present disclosure;
FIG. 2 depicts a circuit diagram of the current sensor according to embodiments of the present
disclosure;
FIGs. 3-4 depict current and magnetic field of the current sensor as a function of time, according
to embodiments of the present disclosure; and
FIGs. 5-6 depict diagnostic flowcharts according to embodiments of the present disclosure.
[0007] The drawings are not necessarily to scale. The drawings are merely representations,
not intended to portray specific parameters of the disclosure. The drawings are intended
to depict typical embodiments of the disclosure, and therefore should not be considered
as limiting in scope. In the drawings, like numbering represents like elements.
[0008] Furthermore, certain elements in some of the figures may be omitted, or illustrated
not-to-scale, for illustrative clarity. Furthermore, for clarity, some reference numbers
may be omitted in certain drawings.
Detailed Description
[0009] Sensors, devices, and methods in accordance with the present disclosure will now
be described more fully hereinafter with reference to the accompanying drawings. The
sensors, devices, and methods may be embodied in many different forms and should not
be construed as being limited to the embodiments set forth herein. Rather, these embodiments
are provided so that this disclosure will be thorough and complete, and will fully
convey the scope of the system and method to those skilled in the art.
[0010] As will be described herein, embodiments of the present disclosure provide for in-situ
verification that a current sensor remains functional and retains calibration. The
sensor status (i.e., working / not working) and loss of calibration may be reported
to a superordinated control system, which can take appropriate action.
[0011] FIG. 1 illustrates a current sensor assembly 100 (hereinafter "assembly") according to embodiments
of the present disclosure. Although non-limiting, the assembly 100 may be used with
a Hall or TMR sensor (not shown). The assembly 100 may include a current sensor 102
coupled to a busbar 104, the current sensor 102 including a coil 108 operable to generate
a magnetic field
Bdiag. The busbar 104 may be made of copper or other electrically conductive material. In
an alternative embodiment, the current sensor 102 may be coupled to a PCB, wherein
the main conductor of the assembly 100 may be a PCB trace, and the diagnostic coil
could be build-up by traces on multiple layers of the PCB.
[0012] During use, the current
Isense flowing through the busbar 104 generates a magnetic field
Bsense, which is detected by the current sensor 102. A value representing the magnetic field
may be delivered to a controller 105, which is operable with the current sensor 102.
By properly orienting the coil 108, the current sensor 102 will receive part of this
magnetic field, superposed to the
Bsense magnetic field. As shown, the coil 108 may generally be oriented orthogonal/perpendicular
to the direction of current
Isense flowing through the busbar 104.
[0013] As shown in
FIG. 2, the current sensor 102, together with the controller 105, receives the sum of
Bsense +
Bdiag, and converts it to a voltage
Vsense +
Vdiag. In some embodiments, a discriminator (DIS) 112 removes
Vsense, keeping
Viag only. Given a certain invariable position of the coil 108 relative to the current
sensor 102, and by setting an appropriate threshold level VREF, it is possible to
determine if the current sensor 102 is operating properly by comparison.
[0014] FIG. 3 demonstrates the relationship between current (I) and magnetic field (B) over time.
More specifically, the current
Idiag can be a pulsed current, with a certain time duration. In this case, the DIS can
separate
Vdiag from
Vsense because the time for Vsense is deterministic referenced to
Idiag. Diagnostics can be run without sense current (e.g., vehicle parked, part of the initialization
sequence) or with sense current (e.g., vehicle driving)
[0015] In
FIG. 4, the current
Idiag can be a periodic current (i.e. sinusoidal), with a certain frequency. In this case,
the DIS can separate
Vdiag from
Vsense because the frequency for Vsense is deterministic referenced to
Idiag. Again, diagnostics can be run without sense current (e.g., vehicle parked, part of
the initialization sequence) or with sense current (e.g., vehicle driving).
[0016] FIGs. 5-6 demonstrate that the diagnostic may be run at the end of the manufacturing process
("Init (EoLine)"), once the relative position of the diagnostic coil referenced to
the current sensor is fixed. Vsense_ref and Isense_ref are recorded. Every time the
diagnostic is run in a normal mode, it is possible to check the calibration status
by comparing the Vsense with the recorded value (e.g., after applying some corrections
depending on other factors such as Isense, T, ...).
[0017] For the sake of convenience and clarity, terms such as "top," "bottom," "upper,"
"lower," "vertical," "horizontal," "lateral," and "longitudinal" will be used herein
to describe the relative placement and orientation of components and their constituent
parts as appearing in the figures. The terminology will include the words specifically
mentioned, derivatives thereof, and words of similar import.
[0018] As used herein, an element or operation recited in the singular and proceeded with
the word "a" or "an" is to be understood as including plural elements or operations,
until such exclusion is explicitly recited. Furthermore, references to "one embodiment"
of the present disclosure are not intended as limiting. Additional embodiments may
also incorporating the recited features.
[0019] Furthermore, the terms "substantial" or "substantially," as well as the terms "approximate"
or "approximately," can be used interchangeably in some embodiments, and can be described
using any relative measures acceptable by one of ordinary skill in the art. For example,
these terms can serve as a comparison to a reference parameter, to indicate a deviation
capable of providing the intended function. Although non-limiting, the deviation from
the reference parameter can be, for example, in an amount of less than 1%, less than
3%, less than 5%, less than 10%, less than 15%, less than 20%, and so on.
[0020] While certain embodiments of the disclosure have been described herein, the disclosure
is not limited thereto, as the disclosure is as broad in scope as the art will allow
and the specification may be read likewise. Therefore, the above description is not
to be construed as limiting. Instead, the above description is merely as exemplifications
of particular embodiments. Those skilled in the art will envision other modifications
within the scope of the claims appended hereto.
1. An apparatus, comprising:
a current sensor coupled to a busbar, the current sensor comprising a coil, wherein
a current flowing through the busbar generates a first magnetic field detectable by
the current sensor, wherein the coil is operable to generate a second magnetic field,
and wherein by orienting the coil, the current sensor will receive part of the second
magnetic field, superposed to the first magnetic field.
2. The apparatus of claim 1, wherein the coil is oriented perpendicular to a direction
of the current flowing through the busbar.
3. The apparatus of claim 1, further comprising a controller operable with the current
sensor, the controller operable to:
receive the sum of the first and second magnetic fields; and
convert the sum of the first and second magnetic fields to a voltage Vsense + Vdiag, wherein a discriminator removes Vsense, keeping Viag only.
4. The apparatus of claim 3, wherein the controller is further operable to determine
if the sensor is operating properly given an invariable position of the coil relative
to the current sensor, and a selected voltage threshold level.
5. A current sensing device, comprising:
a busbar; and
a current sensor coupled to the busbar, the current sensor comprising a coil, wherein
a current flowing through the busbar generates a first magnetic field detectable by
the current sensor, wherein the coil is operable to generate a second magnetic field,
and wherein by orienting the coil, the current sensor will receive part of the second
magnetic field, superposed to the first magnetic field.